Contents of Section
SP-1 Compounds with only monocyclic ring components (Continued)
SP-1.6 Three rings with one spiro atom
SP-1.7 Polyspiro systems with a spiro atom connected to three rings
SP-1.8 Choice of numbering
SP-1.6.1 If there is a choice a smaller ring is numbered before a larger ring.
SP-1.7 Polyspiro systems which include three rings with a single spiro atom and are composed of only monocyclic rings are named using a combination of sections SP-1.4, SP-1.5 and SP-1.6. If there is a choice of numbering the following criteria are considered in order.
SP-1.7.1 Low numbers are selected for spiro atoms.
SP-1.7.2 Low numbers are selected for spiro atoms connecting three rings.
not 86-thiadispiro[184.108.40.206.43]heptadecane (3 is lower than 8)
nor 36-thiadispiro[220.127.116.11.43]heptadecane (3,8 is lower than 3,11, see SP-1.7.1)
SP-1.7.3 Low numbers are selected for the von Baeyer descriptor in the order of citation.
SP-1.8 If there is a choice of names or numbering due to heteroatoms, functional groups or substituents the following criteria are considered in order until a decision is made:
SP-1.8.1 Low locants are allocated for heteroatoms indicated by replacement terms as a set.
not 7-oxa-10-azaspiro[4.5]decane (6,9 is lower than 7,10)
SP-1.8.2 Low locants are allocated for heteroatoms in the order of B-1.1 (ref 5), RB-1.4 (ref 12), R-18.104.22.168 and R-9.3 (ref 6).
SP-1.8.3 Low locants are allocated for non-standard valency indicated by the symbol (ref 11), if necessary in order of decreasing numerical value of the bonding number, i.e. the lower number is assigned to 5 rather than 3. (See also SP-7.)
SP-1.8.4 Low locants are allocated for radical positions, or, if the ring system is a substituent, its point of attachment.
not 6-oxaspiro[4.4]nonan-2-yl (see SP-1.8.1)
SP-1.8.5 Low locants are allocated for cationic sites. (See SP-8 for compounds with ionic spiro atoms.)
SP-1.8.6 Low locants are allocated for the principal functional group.
SP-1.8.7 Low locants are allocated for double bonds.
not spiro[4.5]deca-1,6-dien-10-one (6-one is lower than 10-one, SP-1.8.6)
SP-1.8.8 Low locants are allocated for substituents cited as prefixes regardless of kind.
SP-1.8.9 Low locants are allocated for substituents cited as prefixes in the order of citation.
SP-1.8.10 Low locants are allocated for chirality centres that have the configuration R. (See also SP-9.)
5. IUPAC, Nomenclature of Organic Chemistry, Sections A, B, C, D, E, F and H, 1979 edition, Pergamon Press, Oxford, 1979.
6. IUPAC, A Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993, Blackwell Scientific Publications, Oxford, 1993.
9. Based on a proposal by Andrey Yerin, ACD, Moscow.
11. IUPAC, Treatment of variable valence in organic nomenclature (Lambda convention), recommendations 1983, Pure Appl. Chem. 56, 769-778 (1984).
12. IUPAC, Revision of the extended Hantzsch-Widman system of nomenclature for heteromonocycles (recommendations 1982), Pure Appl. Chem. 55, 409-416 (1983).